Redrock Micro microArm, Long 4" Arms (Black). The Redrock Micro microArm is an adjustable articulating arm for attaching and positioning accessories onto your camera rig. The microArm has 1/4" 20 male screws on each end. The complete articulating knob tightens with a single knob. The long arm is 4" (8" full length). Vendor Part # 2-054-0002